While a Chester County deputy has sued Sheriff Alex Underwood, alleging sexual assault and intentional infliction of emotional distress, the woman has not filed criminal charges, according to court records.

Mary Anne Tolbert, who is on medical leave for stress and anxiety, says in her suit that Underwood coerced her into having sex with him on multiple occasions, then retaliated against her at work when she made it clear she would not allow it to happen anymore.

In a statement issued Monday, Underwood said the allegations “are completely false and I look forward to vigorously defending them through trial if necessary. I would love to comment on this but I have been advised not to do so at this time.”

It is not uncommon for alleged victims in sexual assault cases to file a lawsuit instead of seeking criminal charges, said Colin Miller, a University of South Carolina law school associate professor and associate dean.

People often choose to file a civil suit instead of pressing charges for two main reasons, he said. First, in a civil case, if the victim wins, she can recover monetary damages. If the victim wins in a criminal case, the defendant is punished but the victim doesn’t collect damages.

The second main reason is that the burden of proof is more difficult in a criminal case, Miller said.

In a civil lawsuit, a plaintiff’s burden of proof is the preponderance of evidence, he said. For the plaintiff to win, jurors in a civil case only have to find that it’s “slightly more probable than not” that the incident occurred. In a criminal case, the jury must find it has occurred “beyond a reasonable doubt.”

In the lawsuit, Tolbert alleges the sexual assault incidents took place between February and October 2013.

Another reason many people pursue sexual assault lawsuits instead of criminal prosecution is to avoid the publicity of a trial, Miller said. The majority of assault lawsuits end in a settlement and the case never makes it to court.

Tolbert’s lawyer, Janet Rhodes, declined to comment on Tuesday.

Tolbert is seeking unspecified actual and punitive damages.

Chester police chief responds to lawsuit allegations

Tolbert’s suit includes the locations of several homes where Underwood allegedly coerced Tolbert into having sex with him. One of those identified was the house of Chester Police Chief Andre Williams. Underwood told Tolbert that he had a key to Williams’ residence, according to the lawsuit.

On Tuesday, Williams told The Herald he had no knowledge of Tolbert’s allegations.

Williams said he gave Underwood a key to his former residence so that the sheriff could check on Williams’ home when the chief was out of town.

“I have no knowledge of whatever she’s alleging,” Williams said. “If it occurred, it occurred; if it didn’t, I wouldn’t know. I gave him my keys and trusted that he would watch my residence.”

Williams said he moved from that home about 1.5 years ago, and Underwood returned the key. Williams said his assistant chief now checks on his home when he’s away.